The long-range goal of the project is the elucidation of organizational principles of arthropod visual systems which underlie the extraction of complex visual information. The general approaches are physiological, anatomical, developmental, and behavioral. Intracellular and extracellular recording techniques are used to asses the responsiveness of visual units, both receptors and interneurons, to precisely controlled stimuli which can vary in wavelength, polarization, spatial position, and movement. Intracellular injection of histological markers allows a comparison of structure and function. Anatomical studies, using selective markers, strive to describe the physical relation of receptor types in the retina as well as the repeatability of their location. The relation between receptor projection pattern and physiological properties are also under investigation. Developmental studies seek to understand the principals by which differentiating receptors and brain centers interact to specify the adult pattern. Behavioral studies describe the functional capabilities of the entire system which can then be related to activity at the cellular level.